Data items that are not also UIElement types do not have children; however, they can have a UIElement tree and a corresponding UI Automation tree.

For example, a ListBox can have a collection of strings that contain data items. When those items are processed by an ItemsControl for visualization, a UIElement tree is created for them. This tree can have a corresponding UI Automation tree. After the tree is created, WPF merges the UIElement tree into a UI Automation tree. ItemAutomationPeer works with its UIElement counterpart, if it exists, to obtain more information about the UIElement tree.

Only visible data items, or more precisely, the corresponding UIElement trees, have this dualism. Non-visible data items, which have no corresponding UIElement trees, have only one ItemAutomationPeer.